Great new images from Cassini featuring the Saturn's north pole ! take a look. Now I couldn't leave those unanimated.. All images were received on Earth April 03, 2014. Here is my quick and simple gif (32Mo) :

I truly can't wait to see this one in full res well processed, and in colors!

I still can't imagine the fast and simple algorithm to implement the ringshine (except ray-tracing).

Maybe with two custom plot functions , one fuction of the light direction (from 0 to -1, -1 being the exact opposite direction of the light source), and the other is based on the latitude (if the equator is on the same plan as the rings). You plot entering the two, and get out with a brightness value to add to the planet.

Just a thought reading the thread, no idea how easy it can be implemented.

Do you talk about lookup texture with precomputed lighting? It will work of course, but how to compute this texture? The better way is render planetary rings from many points on planet surface and from many inclination of the sun. But this may be too slow.

Do you talk about lookup texture with precomputed lighting? It will work of course, but how to compute this texture? The better way is render planetary rings from many points on planet surface and from many inclination of the sun. But this may be too slow.

Yeah, some sort of lookup table, or better (and you did think of that as I did not so long ago) a render of the indirect lighting. It wouldn't be as complex as you think because indirect light cast by the rings are diffuse light, which bounce in all directions, and not specular light, which is dependent of the angle of the light source.

Here is a quick render of the indirect lighting at Saturn inclination:

And here is a render at 30° inclination (where the indirect lighting is at its best because little-to-no shadow on the ring) :

(Note for the renders: I rendered this 20x the normal exposure to make the indirect lighting show up better) So at worse there is 30 different textures, but since it only differs by a little, a texture for each 5° interval will be enough, omitting 0° inc (no indirect lighting) and 30° (full indirect lighting).

In other news : Cassini may have witnessed the birth of a new moon in Saturn's rings! [NASA article]